Significance The projections of the primate visual system at maturity are characterized by a high degree of precision that accounts for the remarkable resolving power of this modality. The precision involved in forming the key components of the primate visual system differ from those found in other species and most likely are similar to those in the human. Objectives Our main objective is to describe the events that occur during the formation of specific connections in the primate visual system and to elucidate the mechanisms that regulate developmental specificity. Results During the last year we completed one and began a second study dealing with developmental specificity in the primate visual system. First, we have examined the degree of specificity exhibited by retinal ganglion cell axons growing into their primary target, the lateral geniculate nucleus, in the brain of an embryonic cynomologous monkey. Second, we manipulated that visual pathway and have begun to assess the effects of that manipulation. Future Directions To continue the investigation of the manipulated retinogeniculate pathway at various ages. KEY WORDS visual system, retinal ganglion cells, lateral geniculate nucleus FUNDING NIH EYO3991 PUBLICATIONS Snider CJ, Dehay C, Berland M, Kennedy H, & Chalupa LM. (1998) Monocular enucleation in fetal monkey during the binocular overlap period does not cause an increase in the size of retinogeniculate terminal arbors of the remaining eye. Soc. Neurosci Abst. 24:305. Snider CJ, Dehay C, Berland M, Kennedy H, & Chalupa LM. (1998) Prenatal development of retinogeniculate axons in the macaque monkey during segregation of binocular inputs. J. Neurosci. 19(1) 220-228.